Rescued pelicans cleaned of oil are seen at The Sector Mobile Wildlife Operations Branch.

- Chris Graythen/Getty Images

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Large banks of sand have been built up along the shore line to help prevent oil from coming ashore

- Chris Graythen/Getty Images

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US President Barack Obama speaks after meeting with Coast Guard Admiral Thad Allen (L) and local officials on efforts to fight the BP oil spill at Coast Guard Station Gulfport in Gulfport, Mississippi

- MANDEL NGAN/AFP/Getty Images

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(L-R) Rex Tillerson, Chairman and CEO of ExxonMobil, John Watson, Chairman and CEO of Chevron, James Mulva, Chairman and CEO of ConocoPhillips, Marvin Odum, President of Shell Oil Company, and Lamar McKay, Chairman and President BP America, Inc. are sworn in for a hearing before the House Energy and Commerce Committee June 15, 2010 in Washington, DC. The group of oil executives were scheduled to testify on the topic of 'Drilling Down On America's Energy Future: Safety, Security And Clean Energy.'

The BP oil spill in the Gulf of Mexico has been called the largest environmental disaster in American history. This collection of photos illustrate the massive effort undeway to plug the leaking oil well, contain the further spread of oil, and begin a major environmental cleanup.

U.S. government scientists have estimated that the flow rate of oil gushing out of the ruptured oil well may be as high 40,000 barrels per day, a figure that has been revised over and over since a deep water oil rig operated by BP exploded in April and sunk.

Oil producer BP said that it plans to sell recovered oil from the Deepwater Horizon oil spill, with profits going toward a wildlife protection fund.